Crepe processes, especially double recrepe (DRC) processes, have been used to produce paper products, such as paper towels and wipes, with specific properties. The DRC process involves creping a base sheet or nonwoven web on a drum, printing a polymeric binder on one side of the sheet, flash drying the binder, creping the base sheet on a drum again, printing a polymeric binder on the other side of the base sheet, flash drying the binder, and then creping the base sheet a third time. The base sheet is printed while traveling through gravure nip rolls. Various crepe processes and binding materials used in the processes are known. Examples of such processes are disclosed in U.S. Pat. No. 3,879,257, U.S. Pat. No. 3,903,342, U.S. Pat. No. 4,057,669, U.S. Pat. No. 5,674,590, and U.S. Pat. No. 5,776,306.
In order for the base sheet or web to adhere adequately to the creping drum, polymeric binders used in creping processes are typically emulsion polymers containing surfactants that are based on alkylphenol ethoxylates (APEs).
Due in part to regulations in Europe, regarding use of APE-based products, there has been a need to identify APE-free polymer emulsion binders for use in crepe processes. Known emulsion polymeric binders, that are free of APEs, have not been effective in creping processes, especially DRC processes, because they do not provide the necessary adhesion to creping drums, produce an unacceptable amount of foam, are too low in viscosity, and/or decompose at elevated temperatures causing an unacceptable odor.
Publications, such as U.S. Pat. No. 3,714,099, U.S. Pat. No. 4,745,025, U.S. Pat. No. 4,847,143, U.S. Pat. No. 5,109,063, and JP 94055982 (Abstract), disclose self-crosslinkable vinyl ester-ethylene latexes which can be use as nonwoven binders. Foamability is considered an important property for applying an emulsion binder. However this property is not desired in a creping process.
There is therefore a need for APE-free polymer emulsion binders, for use in crepe processes, that provide the necessary adhesion to creping drums while reducing the unacceptable properties described above.